The objectives of the proposed research are (1) to study cell surface proteins and glycoproteins of polyoma virus and Simian virus 40 (SV40) transformed cells, and (2) to identify and characterize structural and nonstructural gene products of polyoma virus and SV40. In order to label cell surface glycoproteins on intact cells, we intend to transfer radioactive galactose from exogenous UDP-galactose to acceptor molecules on the cell surface by incubating cells in monolayer with purified galactosyl transferase and radioactive UDP-galactose. Conditions for preventing intracellular utilization of free galactose generated by enzymatic hydrolysis of UDP-galactose have been established. Galactosyl transferase has been solubilized from BHK cell homogenates and purified 100 fold. The nondefective adenovirus 2-SV40 hybrid viruses ND1, ND2, and ND4 are a useful tool for identifying nonstructural SV40 gene products. We have started an investigation of the proteins synthesized in HeLa cells infected by these viruses. Our results indicate the presence of several hybrid specific polypeptides in the infected cells. The analysis of their chemical and antigenic properties is in progress.